The subject matter described herein relates generally to substrates having a plural diameter via.
Substrates generally include vias formed therein. The vias are plated with a conductive material that is configured to electrically couple to a contact of an electrical component. The vias electrically couple the electrical component to signal traces extending through the substrate so that the electrical component can direct signals and/or power through the substrate. Often, the vias are formed as dual-diameter vias. The dual-diameter via includes a first portion having a first diameter and a second portion having a second diameter that is greater than the diameter of the first portion. The dual-diameter vias are typically formed by drilling the via using one size drill and then redrilling using a larger size drill. The first portion and the second portion are concentrically aligned. The dual-diameter via improves manufacturing by providing a larger diameter that is easier to plate with conductive materials while maintaining at least some of the electrical properties of a smaller diameter via.
However, conventional dual-diameter vias are not without their disadvantages. In particular, the dual-diameter via may be positioned in proximity to another via. Because the first portion and the second portion of the dual-diameter via are concentric, the first portion and the second portion may be spaced at different distances from the adjacent via. The spacing between the dual-diameter via and the adjacent via may affect the electrical properties of either via. In particular, because the first and second portions of the dual-diameter via are spaced at different distances from the adjacent via, an impedance of each via may be affected so that a target impedance is not met. Additionally, the non-uniform spacing between the vias may increase return loss, noise, and crosstalk between the two vias.
A need remains for a substrate having a plural-diameter via that improves electrical performance.